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Tunable Quantum Transport in Flux-Driven Designer Rings: Role of Hopping Dimerization, Electron Filling, and Phase Architecture
by Souvik Roy and Ranjini Bhattacharya
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Submission summary
| Authors (as registered SciPost users): | Souvik Roy |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202507_00070v1 (pdf) |
| Date submitted: | July 25, 2025, 8:23 p.m. |
| Submitted by: | Souvik Roy |
| Submitted to: | SciPost Physics Core |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
We explore quantum transport in a one-dimensional Su–Schrieffer–Heeger (SSH) ring threaded by an Aharonov–Bohm flux, incorporating a quasiperiodic site potential based on a generalized cosine modulation with both primary and secondary components. Focusing on spinful, noninteracting electrons, we analyze persistent current behavior across a broad range of filling factors, Aubry–Andr´e–Harper (AAH) phase shifts, and hopping dimerizations. Our results uncover a rich interplay of localization–delocalization transitions, driven by the secondary modulation strength, leading to highly tunable and non-monotonic transport signatures. Persistent current is markedly enhanced near the symmetric hopping regime, where quantum interference dominates. In spinimbalanced configurations, we identify regimes exhibiting pure spin current without net charge flow, suggesting potential for dissipationless spintronic functionalities. To the best of our knowledge, this is the first systematic study to examine quantum transport in such a flux-threaded SSH ring with dual-component quasiperiodic modulations, unifying re-entrant localization, spin-current generation, current stabilization, and phase-selective control. Inverse and normalized participation ratios capture the interplay between eigenstate localization and transport behavior, unveiling microscopic origins of suppression and enhancement in current. These findings position the quasiperiodic SSH ring as a versatile platform for realizing controllable quantum interference and spin-resolved transport in low-dimensional systems.
Author indications on fulfilling journal expectations
- Address an important (set of) problem(s) in the field using appropriate methods with an above-the-norm degree of originality
- Detail one or more new research results significantly advancing current knowledge and understanding of the field.
Current status:
Reports on this Submission
Strengths
Weaknesses
- Lack of proper motivation for studying this particular model. Not enough background discussed.
- Too many results but poorly threaded together.
- Lack of arguments to back the numerical observations.
Report
Considering all of these factors I do not recommend this manuscript for publication unless major revision is done to include physical arguments, enough discussions to back the numerical observations.
Recommendation
Ask for major revision
Report
Recommendation
Ask for major revision
We apologize for the confusion and thank the referee for the constructive suggestions. In
response, we have made the following clarifications and additions:
• We have included additional references related to the generalized AAH model.
• In the Introduction, Subsection K, and Appendix D, we now provide a clearer justification and
motivation for the particular model considered in our work
(In rings with random or Aubry–Andr´e–Harper (AAH) site-energy modulation, the persistent
current decreases monotonically with disorder and vanishes in the strong limit, with next-
nearest-neighbor hopping offering only minor enhancement. In contrast, nearest-neighbor hop-
ping with unit-cell modulation exhibits a nonmonotonic response, showing a disorder-induced
peak at half-filling. The generalized AAH (GAAH) model, ϵ_n = λ cos(2πbn+ϕ)/[1−α cos(2πbn+
ϕ)], introduces an additional tunable parameter α that enables independent control of the mod-
ulation strength, giving rise to mobility edges and richer localization characteristics. Although
extensive studies have examined localization phenomena in GAAH systems, the behavior of
persistent current in such settings remains largely unexplored. Motivated by this gap, we inves-
tigate transport within a non-interacting tight-binding framework on the Su–Schrieffer–Heeger
(SSH) lattice incorporating GAAH modulation in a one-dimensional ring geometry.)
• As the manuscript is already quite lengthy, we have added an Appendix where we discuss
in detail the localization-delocalization aspects, state currents, including system size depen-
dence and, more specifically, the rationale for choosing our model and the essential parameter
variations.
• As the results pertaining to the conventional AAH model are well established in earlier studies,
we have duly cited the corresponding references (Refs. 63–65) to acknowledge the existing body
of work.
Author: Souvik Roy on 2025-10-06 [id 5889]
(in reply to Report 2 on 2025-08-22)RESPONSE TO THE COMMENTS MADE BY THE REVIEWER – 2::
Comment: At this stage, the manuscript is not in the position to be accepted. There is not
enough discussion on the background, AAH model and the connection to the quantities studied.
All the results are mostly numerical observations without any strong physical arguments such as
phenomenological pictures to back them. Some observations are completely left without explana-
tion. For example, 1. in Sec. III J, why the re-entrant transitions and what are the expectations
for this transition? 2. Another point is why tuning phi to such values, what is so special about
choosing phi=pi/2. 3. The connection between average IPR and NPR with the current seems to
be mere accidental unless backed with proper physical picture. Considering all of these factors I
do not recommend this manuscript for publication unless major revision is done to include physical
arguments, enough discussions to back the numerical observations.
Reply: We are extremely sorry about the earlier lack of clarity and sincerely thank the referee
for pointing this out. In response, we have carefully revised the manuscript to improve clarity and
organization. The major changes and clarifications are as follows:
• The background discussion, literature survey, and the motivation behind our proposed model
have been elaborated in Subsection K. In addition, the motivation is now presented more clearly
in the Introduction section.
• The content of Section III, Subsection H has been comprehensively rewritten for better orga-
nization, and Subsection J has been revised with a new paragraph to improve readability and
to present the physical insights more transparently.
• The justification for choosing specific values of ϕ2 (such as 0, π, and π/2) is now explicitly
provided in Subsection K
(In this model, we introduce two Aubry–Andr´e–Harper (AAH) phases, ϕ1 and ϕ2, and examine
three representative cases of ϕ2 while fixing ϕ1 = 0, namely ϕ2 = 0, π, and π/2, corresponding
to distinct physical configurations. For ϕ2 = 0, both sites in a unit cell share identical poten-
tials (1 + λ2 cos 2πib), yielding a non-staggered profile. When ϕ2 = π, the potentials become
(1 + λ2 cos 2πib) and (1 − λ2 cos 2πib), forming a staggered pattern. For ϕ2 = π/2, the sites
acquire (1 + λ2 cos 2πib) and (1 − λ2 sin 2πib), producing a mixed cosine–sine landscape. These
three phase choices enable a systematic exploration of how non-staggered, staggered, and hybrid
modulations govern localization, delocalization, and transport characteristics.).
• The connection between the inverse participation ratio (IPR), normalized participation ratio
(NPR), and the charge current has been clearly established. In particular, we present the
current-NPR relation using both the state current-NPR framework and the NPR-eigenstate
framework in Appendix B. We have moved this detailed discussion to the appendix to avoid
further lengthening the main text.
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